Typewriting machine



FIDTQM XR 2.307,33; ,SS Rgfgrn UCCIILII UUU Jan. 5, 1943. l. SZEG ETAI. '2,307,339

TYPEWRITING MACHINE Filed une fr, 1940 s sheets-sheet 1 wlw/M ATTORNEYS MVV/M /74 Jan. 5, 1943. `l. szEG ET AL 2,307,339

TYPEWRITING MACHINE FiiedJune 7, 1940 3 sheets-sheet 2- 52 IIIIIIII' l BY ATTORN EYS Jan. 5, 1943.Y szEG ETAL 2,307,339

I TYPEWRITING MACHINE Filed June fr, 1940 asheets-speet- ATTORNEYS Patented Jan. 5, 1943 Milan, Italy, assign'ors to Universag technische A. G., Glarus, Switzerland, a corporation of Switzerland p Application nine fr, 1940, serial No. 339,248

InBungary'April 23, 1940 sonoma'.V (clim-s4 The invention relates to 'improvements in typewriting machines and particularly toy a' de'- vice adaptable to such machines forwvarying the length of each advancing or spacing step initially impartedto the Writing sheet by'the step-by-step movement of the platen carriagfe,

With normal typewriting machines the1 length of the spacing step of the carriage and thereby of the writing sheet is constant. The .main ob,- ject of the present invention is to provide' a typewriting machine provided with a device of simple design which works reliably and which can be mounted to the existing machine with small cost and which thereon permits its being adjusted to any desired variation of the length of the spacing step imparted to the writing sheet, which spacing step when so adjusted `remains constant during the writing of the respective line, in order to equalize the lengths of the typewritten lines, which normally differ somewhat from each other and to cause -al1 ends of the lines to be in alignment Yso that thetypewritten text has in this respect'the appearance of a printed page.

Another object of the invention is to provide a device which is constructed as a unitary structure attachable to existing typewriting machines, transforming thereby these'machines of known design into improved typewriting :machines having the aforementioned characteristics, such device being referred to as adapter in the claims relating thereto.

The device according to the invention coniprises motion transmitting' means obtaining their impulse from the movement of the carriage and being adjustable at will to vary'the length of the spacing step imparted to the writing sheet to correspond to a predetermined value. These motion transmitting means comprise, according to the invention, positive driving means` for example a chain engaging a chain wheel, a ra-ck engaging a pinion wheel, etc. the chain or rack being fastened to the frame of the typewriting machine, said positive driving means being adapted to rotate a member according to the stepwise displacement of the carriage. the axis of rotation of said rotatable member being xed in relation to the carriage. This rotatable member, which can for example be a toothed wheel driven by the aforesaid chain wheel or pinion wheel or another pinion Wheel keyed to the shaft of the aforementioned wheels. is provided with a piece. for example a pin. in sliding engagement With a member which can be displaced linearly by the aforesaid piece, if the point of for example toothed Wheel.

said shifting member.

` engagement of this piece is adjusted not to coincideflwlth the axis ofrotation ofthe rotatame mmbe`-n` 'I'he rotatable member is journalled to'ensure its'axis of rotation being in a fixed distance4 from the carriage, for example journalled in'a casing rigidlyfastened" to said carriage. The said rotatable member is geared or driven in such a way that it should' make at most onehalf, preferably about one-quarter of a revolution during the 'travel of the carriage corresponding to the maximum number of spacing steps of a line. The point of engagement between the aforesaid; piece and the linearly displace-able member can be adjusted at will in relation to the axis'f rotation of thesaid rotatable member, To l*this end. the toothed Wheel may be provided'wth a threaded spindle rotatably but unslidably mounted thereon and being provided with a knob constituting the adjusting means. Said spindle can have a nut threadedunrotatably but slidably thereon and bearing a pin slidably'engaging'a slot provided in the linearly displaceablenicmber, This memberfmay be displaceable along guiding means mounted in the aforesaidl casing, and provided with indicating means showing thel adjustment f the device. The linearly displace'able member is connected to a shifting "member adapted to correct the displacementbf'the'writing sheet in relation to the frame of thetypewriting machine,independence of the'adjusted distance `of the point of engagement of the members in gagement with the known mechanism adapted to impart the normal step-by-step movement to the rack.

Alternatively. the rack may be fixed to the carriage, as usual, but the means for holding the Writing sheet may be laterally displaceable in relationto the carriage, and connected to In any case, the shifting member corrects the lateral displacement of the writing sheet in relation to the carriage of the typewriting machine, i. e. point of contact of the types acting on the Writing sheet in accordance of this addition or subtraction being adjustablefv Further objects of the invention will appear from the following description and from the accompanying drawings, describing and showing Cross Reierentt is preferably also laterally supported by bearing balls I4. The wheel or segment; I2 is provided with the bearings I5, I5 and in these the spindle I6 is journalled rotatably but not slidrespectively several constructional examples ,of

1-6 show a first embodiment,. in parcorrecting device attached thereto, in perspective view and seen from the rear side;

Fig. 2 shows in elevation the device .according to the invention built to form a lunitary structure, a cover plate being omitted from. the

casing; l Fig. 3 is a vertical section along line III- III inFig. 2; j

Fig. 4 is a vertical section along line IV-IV in Fig. 2; .i 7

Fig. 5 shows a device according .to the invention in different operative positions, .a cover plate being omitted;

Fig. 6 is a diagrammatical front view ofthe device according to the invention;

Fig. '7 shows a vertical section of a cover; Fig. 8 shows a diagrammatical rear view of a modification of the transmission means illusv trated in Figs. 1-6; Y

Figs. 9 and 10 show diagrammatically.further constructional examples in which the length of the spacing step is varied by the alteration of the position of the writing sheet.

In the rst embodiment of the invention .ile lustrated in Figs. 1-6 the variationv in the length of the steps is obtained by the transmission means causing an additional displacement of the carriage relatively tothe rack, the latter being endwise displaceably mounted in thecarriage t permit such displacement. 'l

The motion transmitting means are mounted in a casing I fixed as a unitary structure to the platen carriage 2 of a typewriting machine. 3 denotes the frame of the latter.

The rack 4 moving the carriage 2 is s lideably mounted in the arms of the carriage andcan can be laterally displaced in relation to the carriage 2 to an extent which corresponds to 4at least the sum of the maximal elongation and shortening of all the advancing steps of a line. For example the rack can be displaced laterally in relation to the carriageby the amount of say 10-20 advancing steps.

The pulley wheel 6 is rotatably journalled on a shaft fastened to the carriage 2, thereby constituting a free Wheel. A chain wheel 'I is rotatably journalled in the casing I by means of its shaft` I 0. A chain 8 is fastened with both its ends to the plate 9 fastened to the frame 3. said chain running over the pulley wheel 6 and the chain wheel 1.. The chain wheel 'I has a shaft I!! journalled in casing I. This shaft I0 has keyed t0 its other end a small pinion wheel II positioned inside the casing I and meshing with another toothed wheel I 2 of'larger diameter (Figs. 2 and 3l. This wheel I2 is rotatably journalled in casing I by means of its shaft I3, and

ably, i. e. not being displaceable in the direction of its axis.- The upper len d of this screwthreaded spindle extends through a corresponding elongated slot of the casing I and is provided with a knob II constituting the adjusting means of the device.

Threaded on the spindle I6 is a nut I8, contacting by means .of its flat sliding surface I9 with. the surface of` the wheel I2, and therefore this nut. cannot be rotated in relation to the spindle I6 buscan be displaced in the direction of the axis of this spindle by rotating said spindie. On its side opposite to that bearing the sliding surface I9 the nut is provided with a pin 20 of fpreferably circular cross-section.

The casing I lcontains the sliding piece 22 guided on the guides 2l and linearly displaceable along the se,`guic les, This sliding piece 22 is provided with a slot. 23 constituting sliding engagement' means'for the pin 20 of the nut I8, said pin being positioned in said slot. The sliding piece ,22 i `s"further provided with an arm 24 extending throughva corresponding' slot of the casing I out ,of saidcaSing 'and being connected with the' rack 4. slid'ablymounted in'the arms 5 of the'arriage?.

IOn'je'ach' dvanvcing'step of the carriage 2 the chain wheel 'I is rotated by means of the chain 8 by acertainfa'n'gle corresponding to the advanement of tlie carriage in relation to the frame of the typewriterl Onrotating, the chain wheel 1 rotated the pinion' wheel I.I, andthe toothed wheel I2, and thereby also the spindle I6, which therefore swingsI from its original, for example vertical posltionlshown on,Fig.,2, into another position, together 'withits nut and the pin 2Il of the latter'.

If' the' pin 20 is in the position shown in Figs. 2 and 4 in which position its axis coincides with the axis of rotationof the wheel I2, i. e.. with the axis of the shaft I3, then the rotationof the wheel I2 only rotates the pin 2!! round its own axis and vtherefore the sliding piece 22,is not displaced in relation to the casing I by such rotation ofthepin 20 engaging the slit.2'3. of thesliding piece 22`.A

The step-by-step advance movement is irnparted to the rack 4 in the manner usual in typewriting machines, by means of the known escape mechanism ofthe typewriter. The movement of the rack is-transmitted by means of the arm`24 andthe. parts connected ltherewith to the lcasing I which in the relative positions of its parts shown on Figs. 2 and 4 is undisplaceable in relation to the arm 24, and from this casing themovement is transmitted to the carriage 2 of the typewriter to which the casing is rigidly fastened. If thereforcthe extension 20 is in the position shown in Figs. 2 and 4, thenthe step-by-step movement of the rack 4 isv transmitted by the casing I and all the parts contained therein, no relative movement of the arm 24 and the casing I taking place, and thereforethe movement of the rack being transmitted unchangedly to the carriage 2. Therefore in this case the device according to the invention is out of function, and does not correct the advance movement of the writing sheet.

If, however, the pin 20 has been displaced by rotating the spindle I6 by means oi its knob Il BCH 00m asoma and therefore its axis does not coincide any more with that of the shaft I3, then this pin moves on a curved path on each advance step of the carriage and therefore displaces the sliding piece 22 on each advance step of the carriage in relation to the casing I. The extent of such displacement depends on the distance of the axis of the pin 2 from the axis of the shaft I3.

As the carriage 2 is laterally displaced by the rack 4 by means of the casing I and the parts contained therein, its displacement depends also on the relative displacement of the arm 24 and the casing I. The displacement of the carriage 2 in relation to the frame 3 will therefore be the displacement resulting from the addition or subtraction of the relative displacement of the arm 24 and the casing I to the displacement of the rack 4. Obviously the direction of the relative displacement between casing i and arm 24 depends on the fact, whether the pin is in a position above or below the axis of rotation of the wheel I2, i. e., whether the pin 20 displaces the sliding piece 22 to the right or to the left. The -value of this relative displacement depends on the distance of the pin 20 from the axis of the shaft I3, because the sliding piece 22 is displaced on each step by a value increasing with said distance.

Fig. 5 of the drawings shows a device according to the invention with omission of the covering front plate of the casing in two different workingr positions. In the position' shown with full lines the pin is in a position above the axis of rotation of the wheel I2 in the maximum possible distance from said axis of rotationw In the position shown in dotted lines the pin 2li is below this axis of rotation, also in its maximum possible distance therefrom. Assuming, for ex'- ample, the spindle I6 being in its vertical position shown in the drawing, it will be clear that the rotation of the spindle I6 and thereby the displacement of the pin 20 displaces the sliding piece 22. The direction and extent'of the displacement oi the sliding piece 22 thereforedepends on the direction and extent of displacement of the pin 2li, displacement of the pin 20 upwards resulting in a displacement of the sliding piece 22 to the right and downward displacement lof tie pin 20 displacing the sliding piece to the left.

lThe sliding piece 22 is provided with a scale 2J. The middle of said scale is marked'with 0 and the scale bears numbers increasing to the right and left of said middle, one series of these members also being provided with the mark the other with the mark The covering front pla-te 25 of the casing I is provided with a window 2T through which readings of this scale may be taken (Fig. 6). The scale 25 and the window 21 are preferably mounted in such relative positions that in the position of the device shown in Fig. 2 exactly the middle of the scale can be seen through the window. On displacement of the pin 20 the sliding piece 22 and therefore also the scale 25 is displaced. Therefore the correction of the step-bystep movement of the carriage, i. e. the lengthening or shortening of each advance step obtained by means of the device can be read on this scale, such reading showing the sense and extent oi the correction effected by the device.

The fastening of the casing I to the carriage 2 of the typewriter can be effected, as shown on Fig. 6, by means of the arm 29 of the carriage and by means of the connecting piece 29'.

it is sometimes desirable to displace the carriage 2 at will without thereby actioning the device according to theinvention. ATo this end it is preferable to make the chain wheel 'i rotatable independently of its shaft I0, i. e., providing means for disconnecting at will Wheel I from shaft I0. This may be done for example by providing chain wheel .'I with a further wheel 30 having notches on its circumference (Fig. 3). The rigidly interconnected wheels 1 andr30 are loose on shaft Iii, said shaft being provided with an extension 3 i. This extension bears a two-arm lever 32, 33, arm 32 of this lever engaging on impulse of the spring 34 one of the notches of the wheel 30 andthereby locking wheels 30 and 'I to the shaft I0.

A head 35 extends through a slit provided in the back plate'of the casing I, said head being connected by means of the link piece 36 with a push button 37 extending upwards through thewall caf-thev casingI I. The interconnected parts 35, 36 and 3l arezheld in their upper position shown in the drawing by the spring 38. The head 35 is-positionednear to the path of rotation of the arm.33, and therefore if this arm is under the` head 35 and the button 31 is depressed against'the action of the spring 38, the head 35 moves the arm 33 vdownwards against the action of the spring 34 thereby lifting arm 32 out of the notch of the wheel 30 and disconnecting wheels 30 and 1 from the shaft I0.

The chain wheel l may alternatively be provided; with.. any suitable other locking means, such Vas a simple sleeve rotatable on shaft I0 and provided with suitablelccking means, for example-a-i-:creim which.can be.` actuated by hand to lock said sleeve and therewith wheel l to the shaft. This locking device can be actuated in any position of the wheel 1.

yForprotecting the. cliain,wheel l and the parts connected therewith positioned outside of the ycasing I acover 3S may be provided on the casing. This cover is shown on Fig. 'l and may be fastened to the casing I in any suitable manner and provided with openings 39' for the chain 8. Such covering may also be useful when mounting the device to prevent faulty running or jumping of the chain '8.

Instead of drivingshaft I0 of the pinion' wheel iI by means oi-a chain wheel "I and chain 8 as shown on Figs. l-6, this shaft can also be driven by other positive driving means,for example by a pinion wheel-4d shown on Fig. 8. Said pinion wheel takes the place of chain wheel 'I on shaft I0 and engages a rack 4I fastened to the frame 3 of the typewriting machine.

1n the constructional examples of the device according-to the invention shown and described in connection with Figs. l-'lof the drawings, the carriage of the typewriter obtains an additional or' correcting displacement in order to lengthen or shorten each advance step of the carriage itself. As it is however only essential to correct the displacement of the writing sheet in' relation to the frame of the typewriting machine in order to lengthen or to shorten each advance step of the writing' sheet, the device according to the invention can also be constructed to leave the normal advance movement of the carriage unaltered. i'. e.. uncorrected. and to correct only the advance of the writing sh'eet. To this end the carriage advancing mechanism is left unchanged, and the correction is imparted to a member of the carriage bearing the writing sheet. An example of such a device is shown on Fig. 9.

In the construction shown on Fig. 9 the platen 42 of the carriage! comprises telescopically engaging parts 42 and-543. The part 43'is-inthe form of a sleeve which islunrotatable but: axially slidable in relation to the platenpart42-, To this end, projections 44= of the platen part 42 may engage longitudinal grooves 45.of the sleevel43. Sleeve 43 is provided-Wlth-an annular-*extension 46, engaging'th'e' forked-end of the rod.4'|.\ 'Ilh'e other end ofthis rod is connected with the 'arm 24 extending out offitllef casing of the'device according to the invention. lThe rack? 4 dlsplac ing the' carriage 2 step-by-step is connected'rigidly with the carriagein'this case' and 'therefore the length of each advance step'of'the carriage is constant. The arm 24`of -thefslidingipicen howeveris displaced'on veach advance step,v ac#- cording to the adjustment oi' the-4 pin llfwithfa predetermined valueto Athe right'or tof the left, and therefore' displaces; by mea-ns'of the Irod 41, the sleeve 43 in relation tothe platen'part' 42 by the same valuewnThe advance'stepsoiifthe writing sheet held by the sleeve=`43' are: therefore shortened 'or lengthened ln=re^lation -td'the advance step of the carriage according to lthe adjustment of the deviceaccording to the'invenJ- tion. To enable this, 'the rollers 48-pressi'ngfthd writing sheet to the sleeve-'43 must be' -disposed in amanner-allowing their lateral displacement together with the sleev`e4B,aridtherefore must be slidably mounted on thiwshafts.' "ril 'AIST AlternativelyI itis also 'possible to maketlre platen part'42 laterally dlsplaceable in relation to the carriage'. as shown for' example on Fig. 9 of the drawings. In this case the platen' part 42 is laterally displaced inf relation to-the' carriage 2 iny a-manner similar to'that 'described in connection with Fig. 8,' i."e.,1 byineanslof the rod 41 engaging'with its-iorked-end'thefnnular extension 49 of the platen part-42'.I .The rollers 48 lpressing the writing sheetto the platen part 42 are laterally-displaceable in"relation'.to the carriage in order to be displacedztogether with the platen on lateral displacement of the same. I .f'w'f s In order to use the typewriting machine'provided with any of the above described-devices for varying the spacing steps impartedftothe writing sheet, the writing is. rst-'done with the device in its inoperative position shoWn-inligi in which the axis of the pin 20 coincides.with

the'axis of rotation of the toothed wheel-J2. The written lines will be'unequal in length and they have now to be rewritten toobtaim equal lengths. If it is intended -to Write lines of the equal lengths of say 60 normal .spacing steps,.and. the line written while the device is inv its inoperative position has a length of say 56 normal advancing steps, each of the 56 spacing, steps ofthe .line referred to must be increased'by an increment of t-.l1 of its normal value, so that the-larger 56 I spacing steps will equal the 60 normal steps. In similar manner a line which has thelength of say 62 normal spacing steps hasfto :be shortened by adjusting thedevice to'decrease each spacing step by %2 of its normal value, so that the decreased 62 spacingsteps will equal to the 60 normal spacing steps. A

We wish it to be understood that we do not desireto be limited to the exactdetalls oi construction shown and described, for obvious, modications will occur to a person skilled in the art. ,H i

In the claims aixed to this specication no selection of any particular modiiication of the invention is intended to the exclusion of other modifications thereof and the rightto subsequently make claim to any modification not covered by these claims is expressly reserved.

We claim: I

.-1. In a typewriter or the like having a member movable step by step, an escapement mechanism for Acontrolling the step by step movement of said member, motion transmitting means between the escapement mechanism and said member to varyl the length of Athe step by step movements thereof, comprising a second member controlled by the escapement mechanism and connected to the rst member for movementrelative thereto, a revoluble element movablewith the flrst member, means for imparting a rotative movement to said revoluble element in response to movement of then-iirst member in the direction aforesaid,- al device supported for sliding movement in.the direction aforesaid and connected to the second-member, guide means on said device incltned with respect to the direction of movement thereoha par-t rotatable with the revoluble elementwandzslida'bly engaging said guide means, and means foradjusting said part along the guide means from a position. coincident with the axis ofthe revoluble element to a'position spaced fronnthe axis of the latter element.

2. 4In aftypewriter or the like having a member movable step bystep, anescapement mechanism contrbllingtthe step by step movement of said membenmotion' transmitting means between the escapementmechanism andsaid member to vary the length of .the stepby step movements thereof, .comprising a second member controlled by the escapement mechanism and connected to the iirstmember-for-movement relative thereto, a revoluble. element movable with .the rst membelg-'means` for ,imparting a rotative movement tol said `revoluble' element `in response to move ment of the ilrst memberin the direction aforesaid, aslidesupported for sliding movement alongl path parallel to .the movement of the rstimember and connected .to the second member, said slide vhaving a slot inclined with respect to ,thedirection'of sliding movement thereof, atpart rotatable with-therevoluble element and extendingthrough said-slot for sliding engagementwith opposite side .walls of the latter, and means for adjusting saidpa1t ,along the slot from apositionvcoincident-with the axis of the revoluble yelement to, positions at either side of the axis of the revoluble element.

, 3..,Inavtypewriter or the like having a carriage movable step by step, escapement mechanism for controlling the step. bystep movement of said carriage, .motion transmitting .means be- -tweenthe escapement mechanism and said member to vary the length of the step by step movements thereof, comprising a rack controlled by theescapement mechanism and connected to the carriagefor ,movement relative thereto. a revoluble element movable withthe carriage. means responsive to movement of the carriage for iinpartingarotative movement to said element. a slide supported, for sliding movement in a path parallel,. to the path of travel of the carriage and. connected to said rack, guide means on said slide inclined with respect to the direction of movement of the slide, a part rotatable with the ievoluble element and slidably engaging said guide means, and means .for adjusting said part along the guide meansl from a position coincident with the axis o fthe revoluble element to a position spaced, from the axis of said element.

4. In a typewriter or the like having a member movable step by step, an escapement mechanism for controlling the step by step movement of said member, motion transmitting means between the escapement mechanism and said mem.. ber to vary the length of the step by step movements thereof, comprising a second member controlled by said escapement mechanism and connected to said rst member for movement relative thereto, a revoluble toothed element movable with the first member, a driving gear rotatable in response to movement of the first member in the direction aforesaid and meshing with the teeth on the revoluble element for imparting a rotative movement to the latter, a slide supported for sliding movement in a path parallel to the path of travel of the first member and connected to the second member, guide means on said slide extending transversely to the path of movement of the slide, a part rotatable with the revoluble element and slidably engaging said guide means, and means for adjusting said part along the guide means from a position coincident with the axis of the revoluble element to a position spaced from the axis of the latter element.

5. In a typewriter or the like having a carriage, movable step by step an escapement mech- 'anism for controlling the step by step movement of said carriage, motion transmitting means between the escapement mechanism and said carriage to vary the length of the step by step movements thereof, comprising a rack controlled by said escapement mechanism and connected to the carriage for movement relative thereto, a revoluble toothed element movable as a unit with the carriage, a drive gear rotatable in response to movement of the carriage in the direction aforesaid and meshing with the teeth on the revoluble element for rotating the latter, a slide supported for sliding movement in a path of travel substantially parallel to the path of travel of the carriage and connected to the rack, said slide having an elongated slot extending transversely to the path of travel of the slide, a part rotatable with the revoluble element and extending through the slot for sliding engagement with opposite side walls of said slot, and means for adjusting said part along the slot from a position coincident with the axis of the revoluble element to positions spaced from the axis of the latter element.

6. In a typewriter or the like having a member movable step by step, an escapement mechanism for controlling the step by step movement of said member, motion transmitting means between the escapement mechanism and said meml ber to vary the length of the step by step movements thereof, comprising a second member controlled by the escapement mechanism and connected to the first member for movement relative thereto, a revoluble element movable with the first member, means responsive to movement of the first member in the direction aforesaid and imparting a rotative movement to said revoluble element, a slide supported for sliding movement in a path of travel substantially parallel to the path of travel of the first member and connected to the second member, guide means on said slide extending transversely oi' the path of travel of the slide, a third member carried by the revoluble element and slidable relative to the revoluble element transversely of the axis of said element, said third member having a portion engaging the guide means, and means for adjusting said third member relative to the revoluble element to vary the location of the portion aforesaid of the third member relative to the axis of the revoluble element.

7. In a typewriter or the like having a member movable step by step, an escapement mechanism vfor controlling the step by step movement of said member, motion transmitting means between the escapement mechanism and said member to vary the length of the step by step movements thereof, comprising a second member controlled by the escapement mechanism and connected to the first member for movement relative thereto, a revoluble element movable with the first member, means responsive to movement of the rst member in the direction aforesaid for imparting a rotative movement to said revoluble element, a slide supported for sliding movement in a path of travel substantially parallel to the path of travel of the first member and connected to the second member, guide means on said slide extending transversely of the path of travel of the slide, a nut mounted on the revoluble element for sliding movement transversely of the axis of said element and having a portion slidably engaging the guide means on said slide, and a screw carried by the revoluble element perpendicular to the axis of the latter and threadedly engaging the nut for adjusting the location of the portion aforesaid of said nut relative to the axis of the revoluble element.

8. In a typewriter or the like having a carriage, movable step by step, an escapement mechanism for controlling the step by step movement of said carriage, motion transmitting means between the escapement mechanism and said carriage to vary the length of the step by step movements thereof, comprising a rack controlled by the escapement mechanism and connected to said carriage for movement relative thereto, a revoluble toothed element movable as a unit with the carriage, a drive gear rotatable in response to movement of the carriage in the direction aforesaid and meshing with the teeth on the revoluble element, a slide supported for sliding movement in a path of travel substantially parallel to the path of travel of the carriage and connected to said rack, said slide having an elongated slot extending transversely to the path of travel of the slide, a nut carried by the revoluble element at one side of the latter` for sliding movement transversely of the axis of the revoluble element and having a pin extending parallel to the axis of the revoluble element and projecting through the slot in said slide, a screw carried by the revoluble element with its axis extending perpendicular to the axis of said element and threadedly engaging the nut, and means for rotating the screw to adjust the nut relative to the revoluble element and thereby vary the position of the pin with respect to the axls of the revoluble element.

Izs szEG. ERN KEszLER. 

